The Current State of Duct Leakage Measurement: Field Evaluation of Five Methods

A study of test methods for duct leakage revealed that there is room for improvement in this evolving field.

An increasing number of codes and programs are requiring that air leakage from residential duct systems be measured in order to evaluate the efficiency of the distribution system. For example, proposed Standard 152P from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the Environmental Protection Agency (EPA) Energy Star program for existing duct systems both require that duct leakage be measured (see “Duct Leakage: How Much Is Too Much?” HE Jan/Feb ’01, p. 10), and both specify methods for making this measurement. But how good are these methods, and how much of an impact does a bad estimate have on the actual figure of merit—the distribution efficiency? In 1998, the Seattle, Washington–based HVAC consulting firm Ecotope, where I am a research scientist, undertook a project sponsored by ASHRAE and co-funded by the U.S. Department of Energy to evaluate Standard 152P in the field. This standard uses measurements for duct leakage, conduction loss, fan flow, and so forth and puts the results into a mathematical model to estimate the distribution efficiency. We investigated two questions: (1) how well can the inputs ...